Design for Preaching
by H. Grady Davis. By the "Wittgenstein of homiletics," this 1958 book continues to be one of the best books on preaching. No matter how many years you have been preaching, your preaching will improve as you read and think about what Henry Davis has to say.
Preaching
by Fred B. Craddock
Also by this author is As One Without Authority (on the theoretical side of his narrative style that involves the congregation, and takes seriously their ability to draw their own conclusions) and Overhearing the Gospel (Does the church need to catch up with Hollywood?) as well as two collections of his distinctive sermons:
The Cherry Log Sermons and Craddock Stories
Then there are approaches that vary with the genre of the Biblical Literature being preached which require consideration of interpreting different genres:
Homiletic Moves and Structures
by David G. Buttrick. His homiletic is geared toward constructing sermons that people will actually remember after they leave worship. He also spends half of the book on the art of interpreting the biblical text with regards to preaching, arguing that different literary forms demand different types of sermons.